Puisatron Series M pump from Michael Smith Engineers.

I Tough pumps combine small volume and high pressures

A new range of pumps which offer accurate and adjustable pumping at discharge pressures up to 21 bar and with flows to 650 l/h, has recently been intro- duced by Michael Smith Engineers.

The Pulsatron M Series incorporate a sealed gearbox design to prevent the ingress of liquids and particles and this fea- ture, combined with high quali- ty construction materials, ensures reliability.

Adjustment of desired stroke setting is simple and accurate via a Large, easy-to-hold hand wheel with 1% graduation. An optional microprocessor based MLC stroke-length adjustment allows the pumping rate to vary propor- tional to an external signal.

These pumps incorporate Teflon-faced metal-reinforced diaphragms which are designed and constructed to exacting standards to ensure leak-free pumping and long service life.

Liquid ends are available in PVC, PVDF and 316 stainless steel making the pumps com- patible with most chemicals. Ganging of the pump heads to enable two pumps to run from one motor is also possible.

The Pulsatron M Series cov- ers flows to 650 i/h at maximum discharge pressures between 5 and 21 bar. Liquids with viscosi- ties up to 3000 CP can be pumped, subject to gearbox speed selection.

The pumps are suitable for metering applications in water and effluent treatment or any duty where pumping of small volumes of liquid at high pres- sure is required for long periods.

Contact: Michael Smith Engineers Ltd, Oaks Road, Woking, Surrey, GU21 1 PH, UK Fax: +44 1483 723110.

m Dry screw vacuum pump

Rietschle (UK) Limited has established itself over 50 years, as a world leader in vacuum and low pressure air technology. Its pumps have always been based upon four design philosophies: radial, side channel, rotary vane and Roots (lobe).The company

is now launching a new design principle: a range of dry screw, single-stage vacuum pumps, with a high tolerance to process by-products. The dry screw designs will be known as the Twister range.

Although the principle is not new, being adapted from twin screw air compressor designs, a number of refinements were required to develop these robust units for vacuum duties such as solvent recovery and high vacuum drying, barrel de- gassing in extruders and injec- tion moulders, bottle filling and handling, and vacuum furnace applications.

Within the pump chamber two interlocking, and contra-rotat- ing screw rotors, create an expanding volume which draws gas into the suction. The gas is transported through the pump by the action of the screws, where it is compressed and discharged.

A high ultimate vacuum is created, and the pumps can be operated continuously at any pressure between atmospheric and ultimate vacuum.

Since tolerances are main- tained by precision-ground heli- cal timing gears on the driven and lay shafts, the operation is non-contacting and lubrication is not required in the pumping chamber. To ensure totally oil-free operation, a novel form of mechanical shaft seal was designed for the driven end shaftsThe rotating seal consists of a durable stainless steel bel- lows with a carbon face, whilst the fixed seal is stainless steel with a tungsten carbide face. At the suction end, double lip seals (a PTFE and carbon mix) bear upon a ceramic coated section of the stainless steel shaft sleeve.

The Twister from Rietschie (UK). This standard version is direct coupled. Belt driven models are also available and the Twister can be combined with other vacuum system components such as vacuum boosters and condensers, to form tailor-made systems.

inset: This cutaway view shows the ail-stainless steel, twin parai- iei screw design. its novel mechanical shaft seals ensure totally oil-free operation, which means no process contamination or environmental pollution.

{- WORLD PUMPS AUGUST 1998

Thanks to these design fea- tures, the pump provides a clean and oil-free vacuum; which in turn guarantees no process con- tamination or environmental pollution. Nor are there any costs associated with the waste disposal of contaminated oil or water, which is a drawback of oil-lubricated or liquid ring vac- uum pumps. Noncontact opera- tion results in minimal wear and an extended service life, whilst its slow rotational speed makes for quiet running and low levels of vibration.

The pumping chamber is surrounded by a cooling water jacket and since it has a single stage design, no inter-cooler is required. This means that the pumps are highly tolerant of process by-products - such as liquids, condensates and fine particulate. It also makes for quick and comparatively simple maintenance. Indeed if the pump becomes contaminated by the process it can easily be cleaned, in-situ, by admitting process compatible solvent or steam to the suction. In extreme situations it can be flooded with solvent and left to soak.

Five sizes are currently avail- able, offering nominal dlsplace- ments from 120 m3/hr up to 2700 m3/hr. Ultimate vacuum varies from 0.4 mbar (abs) on the 120, to 0.1 mbar (abs) on the larger models.

A further design feature is the range of materials to suit particular process require- ments.The 720 m3/hr model is available in all stainless steel construction, which is a very unusual option amongst dry- running process pumps.

Standard pump chambers and screws are supplied ln nodular cast iron and PTFE coat- ed. As an additional choice, all process wetted parts can be coated with nickel (20 microns), or with PFA.

In the standard version, Twister is directly coupled to a 50 Hz motor, but belt-driven models and sound enclosure units are available on request. Inverter speed control can be built-in, offering an excellent

means of vacuum regulation and eliminating the need for addi- tional control valves and posi- tioners. Rietschle’s engineering department can also design tai- lor-made systems, where the pumps are combined with vacu- um boosters, condensers and other components.

Contact: Rietschle (UK) Ltd, PWDC, Paddock Wood, Kent TN12 6UU, UK. Tel: +44 1892 035237.

1 Double-headed pumps lead to lower costs

Liquid Dosing Control Ltd has announced the introduction of two new mnges of SERA double- headed diaphragm pumps that it says are suitable for the accurate transfer of free flowing liquids.

These heavy duty pumps manufactured in Germany fea- tnre a single motor, operating two fixed output heads via a robust cast-iron gearbox. The pump heads and wetted parts can be supplied in a wide selection of materials enabling many liquids including aggressive, toxic, flammable, abrasive chemicals etc to be conSdenny handled.

Available with outputs from 450 l/k to 3100 l/hr with oper- ating pressures up to 4 bar, these pumps can easily be installed in any new application where a safe, efficient and even liquid flow is required.

Liquid Dosing Control’s managing director, Mr Peter Hopcroft said,“These new com- pact pumps will yield up to 40% cost and 33% weight sav- ings when compared with the equivalent single headed pump.These pumps are virtual- ly maintenance free and the design has resulted in a reduc- tion of internal moving compo nents, which will maximise operational life.”

Double diaphragms can also be fitted for additional safety The pumps are suitable for use in many different industries including food and drink, pro- cessing, water treatment, chemi- cal and also in hostile operating environments where reliability and chemical resistance is paramount.

Contact: Liquid Dosing Control Ltd, 7 Woodland Drive, Alma Park Industrial Estate, Grantham, Lincolnshire NG31 9DJ, UK, Tel: +44 1476 565512; Fax: +44 1476 590171.

Sera double-headed diaphragm pump.

WORLD PUMPS AUGUST 1998